1. Field of the Invention
The present invention relates generally to the field of communications. In particular, the invention relates to the mobility and recovery of communication services for user terminals in a wireless communication network.
2. Discussion of the Related Art
A wireless communication network is typically comprised of several major portions: a plurality of mobile terminals (such as cellular phones), subscriber information, a radio access network, a switching system and network intelligence (primarily databases). Each mobile terminal contains an electronic card identifying the user, such as a subscriber identity module (SIM) in Global System for Mobile Communications (GSM) networks, or has some other arrangement permitting the user to communicate over the radio access network. The network contains a variety of elements and databases that contain customer information to check authorization for various communication services (e.g., voice, messaging, data and image services) and to process features in accordance with the communication services. The switching system connects mobile terminals to other mobile terminals in the same network or to elements in other networks such as the Internet.
Third-generation (3G) wireless communication networks support advanced mobile terminals and allow a user to subscribe to and access a large number of different communication services. An advanced mobile terminal supported by such a network and using the latest innovations in computers, software, displays and other technologies may access and receive many different advanced multimedia services in addition to conventional voice-based telephony services. These services may be provided by different information sources in other networks and may be based on and built upon Internet applications (e.g., Internet web browsing, video streaming, instant messaging, etc.). The services may include both pull services in which the specific transfer of information is initiated by the mobile terminal (i.e., web browsing, etc.) and push services in which the specific transfer of information is initiated by a network element (instant messaging, sports scores, news updates, etc.).
Technical Specification TS 23.228 V5.0.0 of the 3rd Generation Partnership Project (3GPP), discloses a 3G wireless communication network including an Internet Protocol Multimedia Core Network Subsystem (IMS) able to support multimedia communication services and is hereby incorporated by reference in its entirety as an example network environment. FIG. 1 depicts a general overall view of the main elements providing communication services in an IMS 100. (This depiction shows the functional architecture rather than a physical implementation.) The Home Subscriber Server (HSS) 102 contains user related information such as user identification (UserID), numbering, address information, and a user profile including, for example, subscription information, services and service specific information. The Serving Call Session Control Function (S-CSCF) 101 provides call control, session control and service control for mobile terminals. When a mobile terminal is visiting a network other than its home network, the visited network preferably utilizes a Proxy Call Session Control Function (P-CSCF) that enables the session control to be passed to the home network based S-CSCF providing service control for the mobile terminal. The communication services may be provided by an Application Server 103 within IMS 100 and connected directly to S-CSCF 101 or by an application server in another network or on the Internet, such as an Open Services Architecture (OSA) Application Server 105 connected to S-CSCF 101 indirectly through an OSA application programming interface (API) to OSA Service Capability Server (SCS) 104.
Other than the Cx interface to HSS 102, S-CSCF 101 utilizes the Session Initiation Protocol (SIP) developed by the Internet Engineering Task Force (IETF) or an extension or backward compatible revision thereof for all connections to other network elements. Unlike HyperText Transfer Protocol (HTTP), SIP supports an advantageous event notification scheme. In SIP event notification, the client, such as a mobile terminal, sends a SUBSCRIBE message to a remote element, such as a server, indicating that it wants to receive a notification from the remote element when a specific event has occurred. The SUBSCRIBE message includes To, From and Call-ID headers and an event header to indicate the specific event. Typically, the provider of a communication service designates the event name (i.e., “soccer”) for its service When the specific event occurs, a NOTIFY message is sent to the client. The NOTIFY message copies the To, From and Call-ID headers from the SUBSCRIBE message and the content format is event specific and defined separately for each event. For example, in a presence case like instant messaging in which the specific event is when a specified person logs into the network, the content format is extensible Markup Language (XML) format. SIP is advantageous in wireless communication networks because the event notification scheme can utilize a SIP proxy network and SIP registrars. In such cases, a client subscribes to events using its SIP Uniform Resource Locater (URL) maintained by the SIP registrar instead of the direct contact address (e.g. numeric terminal IP address). The requirement that the NOTIFY message must copy the To, From and Call-ID headers from the SUBSCRIBE message provides reasonable protection against spammers and other unwanted notifications. The client can be set to accept only those NOTIFY messages which have the correct To, From and Call-ID headers.
However, SIP was developed with data-centric networks in mind rather than voice-centric wireless communications networks where value added services are mostly based on supplementary service and Intelligent Network (IN) architectures. The service framework in voice-centric wireless communication networks is quite static and it is quite difficult to add new advanced features. There are problems and disadvantages to implementing SIP in the supporting network and services for a wireless communication network such as IMS 100 shown in FIG. 1. For example, as mentioned in Part 5.1.5 of TS 23.228, HSS 102 of IMS 100 stores all of the subscription information necessary for user terminals and informs S-CSCF 101 whenever the subscription information changes for a user. Conventionally, the subscription information in HSS 102 is used by S-CSCF 101 whenever the user visits another access network or uses a different terminal. However, in some circumstances, such as the SIP event notification scheme described above, certain information generated by the mobile terminal (e.g., To, From and Call-ID header information and Event name from SUBSCRIBE messages) must be maintained in the user terminal rather than in the server(s) providing the subscription service or some other network element. If this information is not available to a user terminal, then the user terminal cannot filter incoming NOTIFY messages and prevent against spamming, etc. In addition to knowledge about ongoing communication services, there may also be other information, such as numerous parameters and/or settings, needed by the user terminal to receive those communication services. The parameters and/or settings may include for instance communication networks parameters, such as General Packet Radio Service (GPRS) parameters or Universal Mobile Telecommunication System (UMTS) parameters, Wireless Application Protocol (WAP) parameters comprising a WAP Gateway address a Uniform Resource Locator (URL) for setup, a home page and favorites, World Wide Web (WWW) parameters comprising a Hyper Text Transfer Protocol (HTTP) proxy address, SMTP/POP3 addresses, public keys, Ipv4, Ipv6, and a Default Classmark for multi-classmark devices. There may also be general information, such as network subscription and authorization information or calling plan information or lists of telephone numbers, stored in the user terminal and which is desired to be available to the user to enable or facilitate communications.
There may be a problem if the user's terminal malfunctions for any period of time (i.e., the terminal crashes and information is lost before it is stored in a memory device) or the terminal has a failure which causes it to lose any information (i.e., memory failure, loss of backup power, etc). There is thus a need for a solution that allows the user terminal to quickly recover in the case of a crash, etc. Furthermore, if a user switches to a different terminal, the new user terminal will not be able to access the stored information in the previous terminal and thus cannot easily continue to receive the subscription services. A user may switch terminals for any reason. For example, they may need or prefer to user different terminals to receive different subscription services, possibly having different quality of service (QoS) requirements, on different respective mobile terminals that are better suited to receiving certain types of services. For example, a user may prefer to use a cellular phone for receiving phone calls and short alphanumeric text messages and to use a laptop computer, with a wireless connection, to receive streaming video. A user may also need or prefer to use different terminals, for example, when receiving services through different access networks such as, for example, wireless local area networks (WLAN), Bluetooth networks or 3G WCDMA radio networks. A user may also simply want to exchange an older mobile terminal in favor of a newer model. In any event, there is a need to allow a user of a new terminal to easily obtain the information stored in a previous terminal when switching to the new terminal.
Although a user could contact a particular service to inform that service of the user's new terminal, that is inconvenient. Furthermore, there would still be a problem in any event if the user subscribes to many communication services and/or different types of communication services. There is thus a need for a solution that allows the information to be available if a user switches between different terminals. It is possible to have the user install the necessary service information when switching to a new terminal to be used. However, manual input is a poor solution because data input on a mobile terminal can be difficult, prone to human errors, and time-consuming. Even if an automatic system solution is used, when there are a large number or different types of communication services, the amount and types of information, parameters, and/or settings may require several automatic systems and it can be quite time consuming to download over a wireless communication network.
For at least these reasons, there is inadequate mobility and recovery of user services when a user switches between different mobile terminals, such as a cellular telephone, a personal digital assistant (PDA), etc., in a wireless communication network utilizing SIP and supporting may different types of communications services. Accordingly, there is a need for providing an effective solution for mobility and service recovery to a user switching between different terminals in a wireless communication network utilizing SIP and supporting may different types of communications services.